High purity processing systems such as those used for processing microcomputer chips and other delicate semi-conductors, have generally required the use of a pressurized inert gas atmosphere such as of argon, or other types of gases such as etching gases, ion implant gases, etc. Many of such gases are also corrosive, flammable, very toxic and require extreme purity to the parts per billion level. The processing gas provides and maintains the sterile conditions required. As a safety measure with such system, as with other gaseous or generally pressurized fluid systems, provision must be made for the safety venting of the fluid or gas under conditions of excessive pressure. Normally such venting is effected by use of a spring loaded valve mechanism such as a poppet which is pushed against a seat by the spring. Excessive pressure build-up, sufficient to overcome the force of the spring, causes the poppet to be removed from the seat and gas to be vented. This system, and those of a similar type, however, inherently permit a degree of leakage wherein the inert processing gas atmosphere is exposed to contaminants from an outside atmosphere, even if only at parts per billion levels. Such micro-level contaminants, while normally of little or no consequence in standard pressurized systems, will detrimentally affect high purity processing systems and particularly those utilized in the manufacture of semi-conductor chips.